Structure One, as its name indicates, was the first building found at the Ness of Brodgar site.
Discovered in 2003, excavation since 2008 has revealed a building with well-preserved walls surviving to a height of around a metre.
Although One may have been built on top of earlier buildings, it did not suffer from the subsidence problems clearly evident in some of its neighbours.
Despite this, the building has a complex history of rebuilding and remodelling with at least three major phases of activity. 
Orientated north-south, it was one of a series of buildings clustered around a central paved area with a single standing stone.
Measuring around 15 metres long and ten metres wide, Structure One’s original incarnation was almost identical to House Two at the nearby Barnhouse settlement. It had a dual-cruciform layout created by corner buttresses and a single set of piers protruding from the side walls.
These formed the same recesses and cells found in its Ness contemporaries and which were partitioned off by orthostats. All but one of these partition slabs were removed during the building’s second-phase remodelling.
The central piers divided the interior into two halves, both of which had their own hearth. Each also had its own entrance, with two offset doorways in the northern and southern ends.
The south entrance was a highly elaborate affair, featuring multiple examples of decorated stone. It was also aligned to the central standing stone, suggesting that if the monolith does not pre-date Structure One it was raised at the same time.
There may have been a third entrance in the eastern wall, north of the pier, but this area was extensively reworked at the start of Phase Two, all but obliterating the evidence.
The building’s c1.6-metre-thick walls were constructed using carefully quarried and selected stone with an inner double-faced wall and an outer revetment, with a midden core between them. The revetment appears to deliberately slope slightly inward – perhaps a construction technique to support the weight of a substantial stone-tiled roof.
In addition to its fine masonry, decorated stone was a major feature in Structure One. Over 70 examples of Neolithic “art” have come from the building to date – the most from any of the excavated structures on site.
Around 2900BC, 200 years or so after Structure One was built, we see evidence of major changes at the Ness.
Foremost, was the construction of Structure Ten, a building that eclipsed the earlier piered buildings. Only a few of these remained in use, but as shadows of their former selves.
Structure One was one and had seen major alterations to its original form.
Whether the building had remained in constant use or had been abandoned for a time is not clear, but the second phase saw it reduced in size when a substantial, curving wall was inserted across the middle of its northern half.
The new wall was raised on top of a series of post-holes suggesting a partition separated the northern section at the end of the primary phase.
A row of three large orthostats was inserted into the new wall, creating another series of end cells and side recesses. These gave the remodelled interior a cruciform layout at the heart of which was a single stone hearth.
Both the original entrances were sealed, and a new door inserted into the building’s eastern wall.
Because the remodelling does not seem to have been necessitated by subsidence or slumping walls there must have been another reason.
Presumably, the building’s role, or significance, within the complex had changed. That said, roof tiles under the phase two wall suggests that Structure One’s roof may have collapsed or been deliberately removed.
In the second phase, Structure One’s hearth remained a focus and activities around it, like all the structures at the Ness, required the periodic repairs and patching of the clay floor.
Around 2800BC, the body of baby was deposited at the southern end of the south-western recess. The infant – which had died at, or near, birth – had been placed on its right side in a pre-existing pit that was re-used for the burial. 
The upper torso had been disturbed at some point after burial, which may explain the absence of a skull. Were it not for a lack of visible cutmarks, however, the fact two vertebrae were missing suggests the head may have been removed before inhumation. 
The infant’s remains were found in the same context as two large animal bones. Although these could simply represent dumped waste, animal bone is frequently found in structured deposits across the site – usually appearing to relate to the foundation and decommissioning of buildings.
Elsewhere in Structure One, for example, the remains of a foetal calf and a neonatal deer had been placed beneath the foundations of the rebuilt northern wall.
Whether the infant’s burial and the deposition of young animals is linked – and if so, what it represents – remains unclear at present.
Evidence points to Structure One being abandoned around 2700BC, before being reoccupied in its third phase.
After the period of abandonment, this final phase of activity saw the construction of a small, semi-circular structure over the top of the hearth.
With a diameter of around three metres, the purpose of this building is not clear but it fits with the pattern noted across the site – a series of smaller, roughly built structures, e.g. Structures Seven, Nine, Eleven, Nineteen and Twenty-Six, raised in and around the dilapidated remains of the earlier buildings.
- 2023: Model of drain between Structures One and Nineteen
- 2022: Model of phase two central orthostat
-  Card, N. and Edmonds, M. (2020) The Later Piered Buildings. In Card, N., Edmonds, M. and Mitchell, A. (eds) The Ness of Brodgar: As it Stands. The Orcadian: Kirkwall.
-  Boyar, A. (2020) The Human Remains. In Card, N., Edmonds, M. and Mitchell, A. (eds) The Ness of Brodgar: As it Stands. The Orcadian: Kirkwall.